1. Field of the Invention
The present invention relates to a delivery member used in paper delivery in office automation machinery, printers and so forth. It also relates to an apparatus making use of such a delivery member.
2. Related Background Art
Apparatus such as electrophotographic apparatus, printers, facsimile apparatus and so forth have a delivery path through which image-receiving media such as recording paper and plastic sheets are delivered. The delivery path comprises roller-like, plate-like or belt-like delivery members.
The image-receiving media are delivered in contact with roller-like, plate-like or belt-like delivery members. Hence the delivery members are required to have a durability. In high-speed recording or color recording, image-receiving media must be delivered with good precision, and hence the delivery members are required to have homogeneous surfaces.
Conventional delivery members such as rollers are exemplified by the following.
(a) Those comprising a steel material having spray-coated thereon a coating solution in which fillers such as metal fine particles have been mixed.
(b) Those comprising a steel material whose surface is plated, thereafter covered with rubber and then coated with Teflon (trademark).
(c) Those comprising a steel material whose surface is made rough by sandblasting or using a laser and then is plated.
(d) Those comprising a steel material whose surface is plated and then coated with aluminum oxide by electrostatic spraying.
(e) Those comprising a steel material whose surface is plated and then subjected to composite plating to form a coating containing SiC or diamond dust.
However, with regard to the above (a), there is a limit in the simultaneous coating of a plurality of members by means of a set of coating robots when a high-grade surface uniformity is required as in the delivery members, if an automation line is adopted in the manufacturing process. Moreover, the state of surfaces of coatings becomes non-uniform because of diffusion of coating compositions to cause a great problem in both the mass productivity and the surface properties.
With regard to the above (b), there is the problem that changes with time as a result of repeated use bring about a deformation of rubber to lower outside diameter precision and cause faulty paper feed and output. This not only lowers the commercial value but also requires a prolonged process in its manufacture, lowers operating efficiency, and results in a high production cost. Thus, there is a great problem in its mass productivity.
With regard to the above (c), the delivery member tends to gather rust on its surface and hence requires a treatment for rust prevention, e.g., plating, carried out in a subsequent step for the purpose of protection from corrosion. In such an instance, the plating is carried out on the sandblasted surface, having a low outside diameter precision, so that the outside diameter precision is further lowered and also the number of manufacturing steps increases. Thus this member can not be mass-produced. In the case of the delivery member comprising a steel material whose surface is made rough using a laser to increase a coefficient of friction, only one member can be manufactured at one time when it is a roller or the like, and moreover it takes a long time for that treatment. Thus this member also can not be mass-produced.
With regard to the above (d), the delivery member can not be stable in the adhesion and uniformity of aluminum oxide and the final outside diameter precision. There is also a limit in the manufacture of uniform-quality goods in large quantities and at a low cost.
With regard to the above (e), there is the problem that impurities tend to be included in a composite plating bath to make the bath unstable and hence the bath can not be durable to repeated use. Moreover, there is a disadvantage of high cost in plating solutions and a problem of a poor uniform dispersibility, bringing about a great problem in manufacturing cost.
In many instances, it is necessary to impart conductivity to the delivery member. For example, conductive paper delivery members are used in copying machines or the like at their paper delivery paths, and resistivity is controlled at the paper delivery paths.
Namely, in the case when a paper delivery member that comes into contact with paper has insulation properties, the paper delivery member produces triboelectricity due to friction between paper and the member in an environment of low humidity, so that toner may adhere to the paper delivery member to soil the paper. In the case when a paper delivery member has a low resistivity, the paper itself comes to serve as a low-resistive element because of its moisture absorption in an environment of a high humidity, so that the charges produced may leak through a transfer guide to cause blank areas of images.
Under such circumstances, in conventional copying machines, as shown in FIG. 10, a delivery member (a guide) 14 comprised of a Ni-coated steel material is grounded through a voltage regulator (a varistor) 12 to have a middle voltage so that toner stains and blank areas caused by poor transfer can be prevented. This method, however, requires an increase in the number of component parts to bring about an increase in operational steps, and hence can not be mass-productive. In the drawing, reference numeral 9 denotes a photosensitive member; 10, toner; 11, a transfer medium; and 13, a transfer corona assembly.